Characterizing cell viability and other cell features can provide useful information with respect to a wide range of applications. However, methods presently employed are quite complex and time consuming. Existing methods make use of permeable fluorophores with an attached ester linker that is subsequently cleaved when present in cells and thereafter emits fluorescens. This technique has however drawbacks including extended incubation times (several minutes). Rhodamin is used to determine the present state of cell viability but do no cross the permeable cell membrane.